How does one train for a marathon or 1/2 marathon?

If you're just starting running, a marathon is an ambitious goal, and it's probably not realistic to expect to begin marathon training until you've been running consistently for at least a year. There are no shortage of training plans and schedules available on the Internet and a quick web search should locate them. If it's your first race though, don't focus on your finishing time but rather on completing the race, feeling good and enjoying yourself. Which brings me to the point on which I'll end this reply - if you don't really like running, why do it? From your question it seems you have plenty of other good cardio options available to you, so if you don't like running don't try to make yourself like it by signing up for a marathon. Stick with what you like and enjoy and you'll be more consistent and get a better workout.

Try to run every other day and keep adding more distances to it and make sure to drink water and strech before the run. Find someone to run with and sign up for the half marathon with you. By the way half marathon is not 7k is 13miles and the full marathon is 26 miles.